JPH05282770A - Controller for spindle motor in magnetic disk device - Google Patents

Abstract

PURPOSE:To realize wholly high-efficient motor driving suppressing a service current at the time of starting in a spindle motor control device used for a magnetic disk device. CONSTITUTION:A voltage control circuit 22 controls a boosting level of a booster circuit 21 so as to generate voltage which is approximately equal to input voltage V1 or lower than voltage in normal rotation. And when it is detected that the speed of rotations of a spindle motor 25 reaches a prescribed value, a voltage control circuit 22 controls a boosting level of a booster circuit 21 so as to generate voltage higher than voltage in normal rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for a spindle motor used in a magnetic disk device.

[0002]

2. Description of the Related Art In recent years, magnetic disk devices (hereinafter referred to as HDD
The demand for lower voltage is also increasing with the miniaturization. For example, a HDD of 2.5 inches or less often requires a voltage of 3V or less.

Here, in the spindle motor for rotating the recording medium (disk) of the HDD, the space for mounting the stator and the magnet for generating the torque of the motor is becoming smaller due to the miniaturization. Usually, the following formula is established when the terminal voltage of the motor is V, the winding resistance of the stator is R, the load current during steady rotation is I, and the back electromotive force during steady rotation is Vemf.

V = IR + Vemf (1) In this equation (1), since the steady-state speed hardly changes, it is necessary to reduce the counter electromotive force Vemf or IR in order to reduce the voltage V. Become. Of these, the load current I is inversely proportional to the back electromotive force Vemf. That is, when the load current I is reduced, the counter electromotive force Vemf
Becomes higher. Therefore, if the winding resistance R can be reduced, the reduction of the voltage V can be compensated.

Therefore, as a conventional method of designing a spindle motor, the torque constant of the motor is determined from the load torque when the motor is steadily rotated at a specified voltage, and the winding resistance is reduced as much as possible in that state. .. That is,
When the motor drive time is divided into the start time and the steady rotation, conventionally, the motor torque is determined according to the steady rotation and the winding resistance is reduced as much as possible to realize the motor drive at a low voltage. .. In this case, there is a problem that the motor torque is insufficient at the time of starting, but that portion is covered by boosting.

FIG. 3 shows the configuration of a conventional motor control device. In FIG. 3, reference numeral 11 is a booster circuit which boosts the input voltage V1 to V2 when the motor is started. Reference numeral 12 denotes a motor drive circuit, which is a voltage V2 boosted by the booster circuit 11.
In accordance with this, the spindle motor 14 is driven. Reference numeral 13 denotes a rotation speed control circuit, which outputs an error signal S4 from the target rotation speed to the motor drive circuit 12 based on the rotation speed signal S3 from the motor drive circuit 12. The spindle motor 14 is a motor for rotating the disk 15.

In such a structure, when a start signal (not shown) is input, the steady voltage V1 is input. This steady-state voltage V1 is adjusted at the time of steady-state rotation as described above, and cannot generate sufficient torque at the time of starting.
When the motor is started, the booster circuit 11 keeps the steady voltage V
Step up 1 to V2. As a result, a voltage V2 higher than the steady voltage V1 is supplied to the motor drive circuit 12, and the spindle motor 14 is started according to the voltage V2. Incidentally, after the spindle motor 14 reaches the steady rotation, it is driven at the steady voltage V1.

[0008]

As described above, conventionally, the starting torque is obtained by boosting the pressure at the time of starting. However, in order to obtain sufficient starting torque,
It is necessary to supply a current flowing at a specified voltage (steady voltage) or more to the spindle motor at the time of startup, and a booster with high power capability is required. For this reason, there are problems such as hindering miniaturization and low voltage of the HDD.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a spindle motor control device for a magnetic disk device, which can suppress the supply current at the time of starting and realize an efficient motor drive as a whole. And

[0010]

SUMMARY OF THE INVENTION The present invention is a spindle motor control device provided with a step-up means for stepping up a voltage to be supplied to a spindle motor. It is configured to control the step-up level of the step-up means so as to generate a voltage that is almost equal to or lower than that at the time of steady rotation, and to generate a higher voltage when the number of rotations becomes higher than that at the time of steady rotation. is there.

Further, according to the present invention, when the rotation speed of the spindle motor is lower than a predetermined rotation speed during the steady rotation, the boosting level of the boosting means is raised so that the rotation speed of the spindle motor becomes a predetermined value. When it is higher than the rotation speed, the boosting level of the boosting means is lowered.

[0012]

According to the above construction, the spindle motor is started at a voltage almost equal to the input voltage at start-up or at a voltage lower than that at steady rotation, and when the number of rotations is high, at a higher voltage than at steady rotation. Driven. Therefore, the current supplied to the spindle motor at the time of startup can be suppressed, and efficient motor drive can be realized as a whole.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the booster circuit 21 includes a voltage control circuit 22.
Boosts the input voltage V1 at the level specified by
The voltage control circuit 22 operates by the input of the start signal S1 and outputs the control signal S2 output from the rotation speed control circuit 24.
The boosting operation of the booster circuit 22 is controlled based on the above.

Further, the motor drive circuit 23 includes a booster circuit 2
The spindle motor 25 is driven according to the output voltage of 1. The rotation speed control circuit 24 detects the current rotation speed of the spindle motor 25 based on the rotation speed signal S3 from the motor drive circuit 23, and outputs an error signal S4 between the rotation speed and the target rotation speed to the motor drive circuit 23. In addition to outputting, the control signal S2 is output in accordance with the number of revolutions of the spindle motor 25.
Is output to the voltage control circuit 22. This control signal S2 is
It is output when the rotation speed of the spindle motor 25 becomes higher than a predetermined rotation speed at the time of starting the motor. The spindle motor 25 is driven by the motor drive circuit 23 and rotates a disk 26 which is a recording medium.

Before explaining the operation of the embodiment, the motor driving method of the present invention will be described in comparison with the conventional method for easy understanding.

As a conventional spindle motor design method, the motor torque constant is determined from the load torque during steady rotation at a specified voltage (steady voltage), and in that state the winding resistance is designed to be reduced as much as possible. .. Then, the shortage of the starting torque is covered by boosting at the time of starting. In this case, it was previously mentioned that a booster with high power capability capable of supplying sufficient current at startup is required.

Here, in the present invention, unlike the conventional design method, it is determined by observing both the torque constant and the winding resistance so that the starting torque can be satisfied at the specified input voltage (steady voltage). .. Since the back electromotive force Vemf is not generated at the time of startup, the degree of freedom is increased and the torque constant can be set large. That is, when the motor driving time is divided into the starting time and the steady rotation time, the present invention determines the motor torque and the winding resistance in accordance with the starting time. In this case, the coil end supply voltage is insufficient due to the generation of the counter electromotive force Vemf during rotation, but this is covered by boosting. That is, when the number of rotations is high, the voltage supplied to the motor is boosted so that the motor can rotate at a steady speed. At this time, it is clear that the starting current can be smaller than that in the conventional method.

Next, the operation of the embodiment will be described.

When a start signal S1 from a controller (not shown) is input to the voltage control circuit 22, the voltage control circuit 22 first generates a voltage substantially equal to the input voltage V1 or lower than that at the time of steady rotation. The boosting level of the boosting circuit 21 is controlled. As a result, the spindle motor 2
5 is driven by the motor drive circuit 23 at a low voltage.

When the disk 26 starts to rotate due to the drive of the spindle motor 25, the state is changed to the rotation speed control circuit 2
Detected by 4. The rotation speed control circuit 24 outputs a control signal S2 when the rotation speed of the spindle motor 25 reaches a predetermined rotation speed when the motor is started. When the voltage control circuit 22 receives the control signal S2, the voltage control circuit 22 generates a voltage higher than that during steady rotation.
Control the boost level of. In this case, the voltage may be increased at one time, but the capacity (power capability) of the booster circuit 21 may be smaller if the voltage is gradually increased as the rotation speed increases.

After the spindle motor 25 reaches a steady rotation by such boosting control, a constant voltage is held, and thereafter, the rotation speed is controlled by the rotation speed control circuit 24 to maintain the rotation speed at that time. .. That is, during steady rotation, the rotation speed control circuit 24 causes the motor drive circuit 2 to operate.
By outputting the error signal S4 with the target rotation speed to the motor drive circuit 23 based on the rotation speed signal S3 from
The spindle motor 25 is rotated at a predetermined rotation speed.

FIG. 2 shows another embodiment of the present invention. Here, it is characterized in that the rotation speed control during steady rotation is performed by a boosting operation. That is, in FIG. 2, the rotation speed control circuit 24a outputs to the voltage control circuit 22a a control signal S5 according to the rotation speed of the spindle motor 25 during steady rotation. The voltage control circuit 22a performs the following control by inputting this control signal S5.

When the rotation speed of the spindle motor 25 is lower (slower) than the predetermined rotation speed, the voltage control circuit 22a controls the boosting level of the boosting circuit 21 so as to raise the voltage and increase the coil current. When the rotation speed of the spindle motor 25 is higher (faster) than the predetermined rotation speed, the voltage control circuit 22a controls the boosting level of the boosting circuit 21 so as to lower the voltage and reduce the coil current.

Even in the case of such a configuration, as in the above embodiment, when the motor is started, the voltage is increased with the increase of the rotation speed, and the mode is switched to the above mode when the predetermined rotation speed is reached. To do so.

[0026]

As described above, according to the present invention, the start-up is carried out at a steady voltage, and the shortage of the voltage due to the generation of counter electromotive force during rotation is covered by boosting, so that the supply current at start-up is suppressed. As a result, even if the power capacity of the booster is low, efficient motor drive as a whole can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration according to another embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional configuration.

[Explanation of symbols]

21 ... Booster circuit, 22 and 22a ... Voltage control circuit, 2
3 ... Motor drive circuit, 24 and 24a ... Rotation speed control circuit, 25 ... Spindle motor, 26 ... Disk.

Claims (2)

[Claims] 1. A magnetic disk device for rotating a recording medium by the driving force of a spindle motor, comprising: a boosting means for boosting a voltage to be supplied to the spindle motor; and a rotation speed detecting means for detecting a rotation speed of the spindle motor. On the basis of the number of revolutions of the spindle motor detected by the number of revolutions detecting means, a voltage which is almost equal to the input voltage at the time of start-up or a voltage lower than that at the time of steady rotation is generated, and when the number of rotations becomes high, the steady rotation A spindle motor control device comprising: a boosting control unit that controls a boosting level of the boosting unit so as to generate a voltage higher than that of the time. 2. The boost control means raises the boost level of the boost means when the rotation speed of the spindle motor is lower than a predetermined rotation speed during the steady rotation.
2. The spindle motor control device according to claim 1, wherein the boosting level of the boosting means is lowered when the rotation speed of the spindle motor is higher than a predetermined rotation speed.